This invention relates to a digitizer tablet employing a cordless transducer/cursor and, more particularly, in a cordless digitizer system in which the position of a cordless transducer/cursor on a tablet is,determined electromagnetically by means of a signal transmitted from the transducer/cursor to the tablet at a frequency, to apparatus for wirelessly transmitting the status of a non-positional function of the transducer/cursor to the tablet comprising, status means for representing the status of the non-positional function of the transducer/cursor as a binary number comprising at least one parallel binary bit; a parallel-to-serial shift register connected to receive the binary number in parallel and output a serial stream of binary pulses representing the binary number; and, wireless transmission means for separately transmitting the serial stream of binary pulses.
The typical prior art digitizer has a tablet and a transducer/cursor in the form of a pen or a puck. The position of the transducer/cursor on the surface of the tablet is sensed and an operator's desire to accomplish one or more tasks is signaled by operating button activated switches or by pressing the transducer/cursor (in the case of a pen) against the tablet to operate an associated pressure-activated switch. Early transducer/cursors were connected to the tablet by means of a multi-conductor cable through which the positional and button/pressure information flowed virtually without problem.
More recently, cordless transducer/cursors have become popular. Prior art cordless transducer/cursors have attempted to use phase and/or frequency changes to transmit the non-positional status of the transducer/cursor with respect to such things as buttons pushed, pen pressure, or the like. Unfortunately, phase and frequency changes are very prone to false reading resulting from outside influences such as metal objects in the area, noise, etc.
Wherefore, it is an object of the present invention to provide a cordless digitizer transducer/cursor in which wireless transmission of a serial digital data stream is used to indicate non-positional transducer/cursor status information.
It is a further object of the present invention to provide such a cordless digitizer transducer/cursor in a reliable lowpower, low price format.
It is a further object of the present invention to provide a method of wirelessly transmitting non-positional transducer/cursor status information from a transducer/cursor to an associated digitizing tablet which is error resistant.
Other objects and benefits of the invention will become apparent from the detailed description which follows hereinafter when taken in conjunction with the drawing figures which accompany it.